1. Technical Field of the Invention
This invention relates to an in-vehicle charge control system that controls charging operations for an in-vehicle battery.
2. Related Art
Conventionally, as disclosed in Japanese Unexamined Patent Application Publication No. 2003-209935, there is known a charge control apparatus, which is composed of battery-state (voltage, current, and temperature) detection means, regulated-voltage control means (a microcomputer) and a regulator, controls a regulated voltage so that an integrated value of a discharging/charging current is zeroed. This apparatus is intended to prevent deterioration in fuel efficiency and battery liquid loss due to overcharge by controlling the regulated voltage so that the integrated value of the discharging/charging current is zeroed to thereby restrain power generation.
There is also known, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-57853, another control apparatus, which is composed of driving-state (accelerated state, decelerated state, and low speed running state) determination means, battery-state determination means and power generation restraint means, determines a state of charge of the battery in the decelerated state, and determines to restrain power generation in the accelerated state on the basis of the determination result of the state of charge. This apparatus allows power generation control to be performed as a function of a vehicle running state on the basis of the battery state.
The above disclosed apparatuses allow the battery charge/discharge integrated value to be zeroed for a light electrical load, thereby improving the fuel efficiency and maintaining the battery charge level simultaneously. However, a heavy electrical load, such as an air conditioner or a heater, should be taken into account under practical use conditions, where a battery charge/discharge integrated value is not balanced (or zeroed). As a result of a resultant drop in battery charge level, the power generation control for the power generation restraint gets disabled.
As for combination of the above techniques with an idle stop function that is becoming more commonly used to further improve the fuel efficiency, since the power generation is stopped during idling, the battery charge level is further lowered. As a result of such a further drop in battery charge level, both the idle stop function and the power generation control for the power generation restraint become disabled, which prevents enhancement of the fuel efficiency.
In consideration of the foregoing, exemplary embodiments of the present invention are directed to providing a charge control system capable of both maintaining battery charge level and enhancing fuel efficiency under practical use conditions.